Soldering iron



Aug. 9, 1938. F. M. KIRKPATRICK I '2,126,559

SOLDERING IRON 'Filed March 30, 1934` '.50 soldering iron, although it is to be understood is capable of being forged and rolled, and thus 50 "Patented Aug. 9, 193s Y. l 2,126,559

.UNITED `s'rxri-s PATENT OFFICE SOLDERING IRON Floyd M. Kirkpatrick, Erie, Pa., assignor to General Electric Company, a corporation of New York Application March 30, 1934, Serial No. 718,226 s claims. (ci. 11a- 105i This invention relates to soldering irons and heating unit il in heat conducting relationwith it has for its object the provision of an improved the tip l and a handle l2 which supports the working tip in soldering irons which materially heating unit and the working tip. lengthens the life of-the iron. As previously pointed out, the soldering tip I0 Soldering irons, heretofore generally used, have arranged in accordance with this invention is 5 been provided with working tips made of copper, made of an alloy consisting mainly of copper, but because this material has a very high heat concontaining a minor quantity of beryllium and the ductivity, which characteristic is desirable for remainder of a metal having the effective alloyeillcient operation .of the iron. Copper, ing characteristics of cobalt. At present, the prehowever, possesses the disadvantages that it ferred alloy consists of about 97% copper, about 10 rapidly corrodes or decompeses by reacting with 2.6% cobalt andabout 0.4% beryllium. 'I'his alloy certain soldering fluxes heretofore used, such as 'is treated by heating it forapproximately one ammonium chloride; oxidizes when lheated while hour at approximately 900 C. and then quenchidle between the soldering operations; and moreing it in water, and thereafter reheating to ap over, rapidly wears away due to its mechanical proximately 500 C. for one or two hours and then 15 softness, f allowing it to cool. The `rate of cooling from the This invention contemplates the provision of an 500 C. temperature seems to be immaterial, and improved soldering iron working tip which, while so it may be air cooled. it has suitable thermal characteristics for eili- The working tip I0 formed of the above alloy cientoperation, is substantially free from disintreated in the above-described fashion is far 20 tegration or decomposition by oxidation and by superior to the copper working tips heretofore soldering fluxes and the like and which has a very generally used. i good mechanical strength, that is, which is relaz Its ability to resist corrosion or decomposition tively hard and wear resistant. In other words, due to mixing with the various uxes that are' this invention `contemplates the provision of an used in soldering operations is remarkable as improved soldering iron tip which is just as efllcompared with that ofthe copper tip. cient in its operation as the copper tip, and which It is not definitely understood at this time just has a considerably longer life than the copper rwhy the soldering tip possesses such a marked til). capacity to resist corrosion and deterioration by In accordance with this invention, the working fluxes, but it hasbeen denitely established that 30 tip 'of the soldering iron is made of an alloy conit lpossesses this characteristic. sisting mainly of copper, but containing a minor Likewise,` tips arranged in accordance with this quantity of beryllium, and the 'remainder of a invention resist oxidation when heated While idle metal having the effective alloying characteristo a` marked degree. It is thought that this isv tics of cobalt. At present, the preferred alloy due to the fact that when this tip oxidizes, a pro- 35 consists 0f about 97% Copper; abllt 2.6% cobalt tective oxidized layeris formed over the tip which and about 0.4% beryllium. resists further oxidation. With the copper tip, For a more complete understanding of this inon the other hand, the oxidized layersA peel oii 4vention, reference should be had to the accomwhen the temperature of the tip changes, thereby `40 panying drawing in which Fig. i is an elevation exposing fresh coppersurfaces to the atmosphere 40- of a solderingiron embodying this invention,v which in turn are oxidized. A portions of the iron being shown in section s'o as Moreover, this tip has a Brinell hardness of to illustrate certain details of construction; and between 200-220 as compared with the average Fig. 2 is a perspective taken on an enlarged scaleA Brinell hardness of 30 in soft copper, and 90-100 of a working tip used in the soldering iron of Fig. in cold worked copper, and hence, is much more 45 1 and arranged in accordance with this invenwear resistant than the copper tips. tion. 4 Moreover, while the alloy of which this tip is Referring to the drawing, this invention has made has considerable mechanical'strength and been shown as applied to an electrically heated resistance to wear,` it is readily machinable and that the invention is not limited to soldering irons may be formed into soldering tips having any which are'heated by electricity, but is applicable desired suitable shape. to soldering irons in general, irrespectivel of the Becauseit resists corrosion and oxidation and mode of heating the iron. As shown, the solderhas a relatively high we ar resistance, this tip ing iron comprises a working tip I0, an electrical has a life much longer than the standard copper 55 tips heretofore used. In a particular soldering application, it has been found that a standard calorired copper tip after about six weeks of use The tip arranged in accordance with this invention has a heat conductivity of approximately 45% that of the copper tips used heretofore. It has been found that while the heat conductivity of the tip is less than that of the copper tips, it nevertheless is just as emcient in its soldering operation as is the copper tip. This is probably be- .cause the tip of this invention has a larger heat capacity than that of the copper tips. At any rate it has been found that the tip of this invention will actually melt solder at a somewhat faster rate than will copper tips.

In brief, therefore, the advantages of this tip known at the present time reside in its ability to resist corrosion and decomposition by reacting with fluxes, its ability to resist oxidation when not in use, its ability to solder just as eiiiciently as the copper tips heretofore generally used, and its ability to resist mechanically the wear to which tips are subjected.

As pointed out above, the soldering tip arranged in accordance with this invention has general application. In the soldering iron disclosed in this application, the soldering tip I is secured directly to the heating unit I I. The heating unit II, as shown, comprises a' heating element I3 which preferably will be of the sheathed type, such as described and claimed in United States patent t0 C. C. Abbott No. 1,367,341, dated February 1, 1921. This unit in brief comprises a helical resistance heating element Il encased within a metallic sheath I and embedded in and supported in spaced relation with respect to the sheath by means of a suitable electrically insulating, heat refractory and conducting material, such as magnesium oxide. The heating element Il, as shown, is formed in a plurality of convolutions, the terminal ends Ila and lib of the convolutions being brought -out at the handle end of the soldering iron. The heating coil is embedded in a heat conducting mass of. material I1, which preferably will be formed of copper. The tip I l, as shown, issecured directly to the heat- I ing body II in end to end relation with it. Pref-- erably, the' tip will be silver soldered to the bod II with a butt Joint, as shown.

Secured in the mass of material I1 at the handle end is a suitable metallic member 20 which is provided with spaced apertures (not shown) for receiving the two ends Ita and IIb of the heating unit.

It will be understood that the terminals (not shown) of the heating unit will be brought to these ends of the heating element and that they will be threaded through suitable insulators l2| interposed between the heating element and the handle Il. These members 2| are provided with spaced apertures through which the terminals arepassed, and through the handle end of which suitable electrical supply leads (not shown) are fed to the terminals.

'I'he heating element II with the tip secured thereto is secured to the handle I2 by means of a hellcally shaped member 23, helical V-shaped grooves 24 and 25 being provided in .the metallic member 2l of the heating unit and the handit? I2 respectively arranged to receive one or more of the end turns of the helical member 23.

A suitable twin supply conductor 2B is threaded through a bore (not shown) provided for it in the handle I 2 and is electrically connected with the above-mentioned supply leads connected with the terminals of the heater.

The specific construction of the heating unit I I, the handle I2 and the mechanical connection between the handle and the heater', the connections between the supply leads and the terminals and between the electrical supply conductor 26 and the leads form no part of this invention, and it is believed to be unnecessary, therefore, to describe these elements in greater detail.

It is to be understood, however, 'that the mass of heat conducting material Il may be formed. of the above copper-beryllium-cobalt alloy as well as the tip I0. However, it is generally more economical to make the tip I0, which alone contacts the fluxes and the work, as a separate member and of the alloy, while the body II will be formed of copper.

In this particular iron where the tip I0 is silver soldered to the body Il, the tip may be treated conveniently in the following manner. The soldering occurs over a temperature range of 820 to 870 C. Complete fluidity of the solder occurs at approximately 870 C. Assoon as the solder has solidified sufiiciently to hold the tip, the tip is quenched in water. The temperature just previous to quenching will probably be around 825 C. I'he quenched tip is then drawn, which operation may be accomplished either by reheating the quenched tip by external heating means to approximately 500 C., holding it at this temperature for one or two hours and then cooling it in air from 500 C.; or if the capacity of the tip is such as to operate at- 500-525" C. when idle, the heating unit II may be used to draw the quenched tip for an hour or two 'at 500 C. after which the tip is allowed to cool in air.

I1' a removable tip is used, such as a tip screwthreaded onto the heating unit, as described in the U. S. patent to C. C. Abbott, No. 1,708,995, and dated April 16, 1929, the tip may be treated either before or after it is machined to shape and size and to provide it with threads, and

preferably as described in a previous portion of this speciilcation; 'I'hat is, the treatment will consist in heating the tip for approximately one hour at 900 C. then quenching in water and then reheatlng the quenched tip at 500 C. and holding the tip at this temperature for one or two hours; the tip is then allowed to cool in air from 500 C.

While it is preferable to use a copper-cobaltberyllium alloy of substantially the above-specied composition, it is to be understood that other l 1. A soldering iron comprising a working tip formed of an alloy consisting substantially of copper, beryllium and cobalt, said copper constiamarre tilting approximately 97% of said alloy, said beryllium constitutingr an appreciable amount ol' said alloy, but less than 1% thereof, and said cobalt constituting the remainder of said alloy.

2. A soldering iron comprising a working tip formed of an alloy consisting substantially oi copper, beryllium and cobalt, said beryllium and cobaltconstituting from about 0.4% to about 3% of said alloy, the percentage of beryllium in said alloy being less than the percentage of cobalt in said alloy, and said copper constituting the remainder of said alloy.

3. A soldering iron tip formed of an alloy consisting of copper, beryllium and cobalt, the copper constituting approximately 97% of said alloy, the beryllium not appreciably more than 1% of said alloy and the cobalt constituting the remainder of said alloy.

4. lin a soldering iron, a working tip formed of an alloy of about 07% copper, about 2.6% cobalt and 0.4% beryllium.

5. In a soldering iron, a Working tip of relatively great longevity formed of copper, cobalt and beryllium alloy oi about 97% copper, about 2.6% cobalt and 0.4% beryllium and having a lBrinell hardness of approximately 20G-220 and a heat conductivity of about 45% that of copper.

6. A soldering iron tip formed of an alloy consisting mainly of copper with small amounts of beryllium and cobalt to give the tip increased resistance to wear and increased resistance to oxidation and disintegration when subjected to temperatures higher than normal operating tem- FLOYD M. lili ATRICK. 

